1. Field of the Invention
The present invention relates to an image processing apparatus and method for a printer interface for expanding images based on command data which are designated by image processing instructions, such as used in a page description language, from a computer and for outputting the expanded images to a printer.
2. Description of the Related Art
A conventional printer system for expanding color images according to page description language and for outputting the expanded images to a color printer expands the color images on each color plane based on the colors (cyan, magenta, yellow and black, or red, green and blue) which are designated by page description language.
However, in the above-mentioned conventional example, when black characters or black pictures are created, toner or ink of the colors such as cyan, magenta and yellow are overlapped and then outputted. Therefore, there are the following problems.
(1) The amount of overlapped toner or ink is too great so that toner scatters or the recording paper is crumpled by the ink.
(2) Color fringing occurs in the contours of the characters.
In view of the foregoing problems, an object of the present invention is to provide an image processing apparatus and method for a printer system for clearly printing edge portions of a black character or image. Another object of the invention is to prevent the toner from scattering or the paper from being crumpled by the ink and for further preventing color fringing of the contours of the characters.
To achieve this object, the present invention is provided with the following construction.
That is, a printer interface comprises receiving means for receiving command data from an external device; expanding means for expanding image data according to the received command data; storing means for storing the expanded image data; determining means for determining whether or not the expanded image data represents a specific-color pixel; extracting means for extracting a pixel in an edge-portion from the expanded image data; and processing means for processing the expanded image data and outputting the processed image data to a printer, wherein said processing means performs a first process on a pixel which is determined as the specific-color pixel and is in the edge portion and performs a second process, different form the first process, on a pixel which is determined as the specific-color and is not in the edge portion.
A printer interface may also comprise expanding means for expanding color image data according to a given instruction; storing means for storing the expanded color image data; determining means for determining whether or not the expanded color image data represents a black-color pixel; extracting means for extracting a pixel from an edge portion of the expanded color image data; and output means for outputting the expanded color image data at an edge portion of the black color in black only to a printer and for outputting the expanded color image data at a non-edge portion of the black color in a half tone or a pseudo-half tone as well as in black to the printer, according to the results obtained by said determining means and said extracting means.
The present invention also provides a printer including the whole of or part of construction as stated above. Further, the present invention provides a printer including input means or creating means for the image data.
In the above-mentioned constructions, even when black characters or characters printed in a black reverse are expanded, the contours thereof can be printed in black only and the inside or the outside of the contours which are designated to be printed in black color can be printed in the three colors such as magenta, cyan and yellow in a half tone or in a pseudo-half tone as well as in black.